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This article lists quotas and limits in Azure Event Grid.
Note
The following limits listed in this article are per region.
Event Grid throttle limits
Event Grid offers a Standard tier and a Basic tier. The Event Grid Standard tier enables publish-subscribe by using Message Queuing Telemetry Transport (MQTT) broker functionality and pull delivery of messages through the Event Grid namespace. The Event Grid Basic tier enables push delivery by using Event Grid custom topics, Event Grid system topics, Event Grid domains, and Event Grid partner topics. For more information, see Choose the right Event Grid tier. This article describes the quota and limits for both tiers.
Event Grid namespace resource limits
Event Grid namespaces enable MQTT messaging and HTTP pull delivery. The following limits apply to namespace resources in Event Grid.
| Limit description | Limit |
|---|---|
| Event Grid namespaces per Azure subscription | 50 |
| Maximum throughput units (TUs) per Event Grid namespace | 40 (To request an increase beyond 40 TUs, contact Microsoft at askmqtt@microsoft.com.) |
| IP firewall rules per Event Grid namespace | 16 |
MQTT limits in the Event Grid namespace
The following limits apply to MQTT in the Event Grid namespace resource.
Throughput units define the ingress and egress event rate capacity in namespaces. You can use TUs to control the capacity of your namespace resource for message ingress and egress.
| Limit description | Limit |
|---|---|
| MQTT sessions per Event Grid namespace | 10,000 per TU |
| Sessions per Event Grid namespace | 10,000 per TU |
| Session expiry interval | 8 hours, configurable on the Event Grid namespace |
| Inbound MQTT publishing requests per Event Grid namespace | 1,000 messages per second per TU |
| Inbound MQTT bandwidth per Event Grid namespace | 1 MB per second per TU |
| Inbound MQTT publishing requests per session | 1,000 messages per second |
| Inbound MQTT bandwidth per session | 1 MB per second |
| Inbound in-flight MQTT messages* | 1,000 messages |
| Inbound in-flight MQTT bandwidth* | 64 KB |
| Inbound HTTP publishing requests per Event Grid namespace | 500 messages per second per TU |
| Inbound HTTP bandwidth per Event Grid namespace | 512 KB per second per TU |
| Inbound HTTP publishing requests per session | 500 messages per second |
| Inbound HTTP bandwidth per session | 512 KB per second |
| Inbound in-flight HTTP messages* | 500 messages |
| Maximum Retain message size** | 64 KB |
| Maximum Retain message per TU | 10,000 messages or 640 MB (whichever is reached first) |
| Total Retain storage per TU | 640 MB |
| Retain message expiry (MQTT 3.1.1) | 365 days (default) |
| Retain message expiry (MQTT 5.0) | Configurable by using the message expiry interval with a range of 0 to 31,536,000 seconds (365 days) |
| Outbound MQTT publishing requests per Event Grid namespace | 1,000 messages per second per TU |
| Outbound MQTT bandwidth per Event Grid namespace | 1 MB per second per TU |
| Outbound MQTT publishing requests per session | 100 messages per second |
| Outbound MQTT bandwidth per session | 1 MB per second |
| Outbound in-flight MQTT messages* | 100 messages |
| Outbound in-flight MQTT bandwidth* | 64 KB |
| Maximum message size | 512 KB |
| Segments per topic/topic filter | 15 |
| Topic size | 256 B |
| MQTTv5 response topic | 256 B |
| MQTTv5 topic aliases | 10 per session |
| MQTTv5 total size of all user properties | 32 KB |
| MQTT connect rate per client session | 1 connection attempt per second per client session |
| MQTTv5 content type size | 256 B |
| MQTTv5 correlation data size | 256 B |
| Connect requests | 200 requests per second per TU |
| MQTTv5 authentication data size | 8 KB |
| Maximum Keep Alive interval | 1,160 |
| Topic filters per MQTT SUBSCRIBE packet | 10 |
| Subscribe and unsubscribe requests per Event Grid namespace | 200 requests per second |
| Subscribe and unsubscribe requests per session | 5 requests per second |
| Subscriptions per MQTT session | 50 |
| Subscriptions per Event Grid namespace | 1 million |
| Subscriptions per MQTT topic | Unlimited, if they don't exceed the limit for subscriptions per Event Grid namespace or session |
| Registered client resources | 10,000 clients per TU |
| Certificate Authority certificates | 10 |
| Client groups | 10 |
| Topic spaces | 10 |
| Topic templates | 10 per topic space |
| Permission bindings | 100 |
* For MQTTv5, learn more about flow control support.
** Retained messages count against the total MQTT storage quota for the namespace. When the quota is reached, publishing new retained messages fails until existing messages are expired or deleted (for example, via an empty payload publish).
Events limits in the Event Grid namespace
The following limits apply to events in the Event Grid namespace resource.
| Limit description | Limit |
|---|---|
| Event Grid namespace topics | 100 per TU |
| Event ingress | 1,000 events per second or 1 MB per second per TU (whichever comes first) |
| Event egress (push and pull APIs) | Up to 2,000 events per second or 2 MB per second per TU |
| Event egress (acknowledge, release, reject, and renew lock APIs) | Up to 2,000 events per second or 2 MB per second per TU |
| Maximum event retention on Event Grid namespace topics | 7 days |
| Subscriptions per topic | 500 |
| Maximum event size | 1 MB |
| Batch size | 1 MB |
| Events per request | 1,000 |
Custom topic, system topic, and partner topic resource limits
The following limits apply to Event Grid custom topic, system topic, and partner topic resources.
| Limit description | Limit |
|---|---|
| Custom topics per Azure subscription | 100 When the limit is reached, you can consider a different region or consider using domains, which can support 100,000 topics. |
| Event subscriptions per topic | 500 This limit can't be increased. |
| Publish rate for a custom or a partner topic (ingress) | 5,000 events or 5 MB per second (whichever comes first) An event is counted for limits and pricing purposes as a 64-KB data chunk. So, if the event is 128 KB, it counts as two events. |
| Event size | 1 MB This limit can't be increased. |
| Maximum event retention on topics | 1 day This limit can't be increased. |
| Number of incoming events per batch | 5,000 This limit can't be increased. |
| Private endpoint connections per topic | 64 This limit can't be increased. |
| IP firewall rules per topic | 128 |
Domain resource limits
The following limits apply to the Event Grid ___domain resource.
| Limit description | Limit |
|---|---|
| Domains per Azure subscription | 100 |
| Topics per ___domain | 100,000 |
| Event subscriptions per topic within a ___domain | 500 This limit can't be increased. |
| Domain scope event subscriptions | 50 This limit can't be increased. |
| Publish rate for a ___domain (ingress) | 5,000 events or 5 MB per second (whichever comes first) An event is counted for limits and pricing purposes as a 64-KB data chunk. So, if the event is 128 KB, it counts as two events. |
| Maximum event retention on ___domain topics | 1 day This limit can't be increased. |
| Private endpoint connections per ___domain | 64 |
| IP firewall rules per topic | 128 |
Related content
- For quotas and limits of all Azure services, see Azure subscription and service limits, quotas, and constraints.